Bell end forming and troweling ring



March 26, 1957 FIG R. V. EDWARDS Filed Jan. 22, 1954 FIG. I. H

BELL END FORMING AND TROWELING RING 38 44 33 4 4| l I IIJIHII 5 1| I l INVENTOR ROBERT v. EDWARDS ATTORNEYS Unite BELL END FORMING AND TROWELING RING Application January 22, 1954, Serial No. 405,561

6 Claims. (Cl. 25--39) This invention relates to the art of centrifugal casting of concrete pipe and, more particularly, to the forms used in casting pipe.

In the manufacture of centrifugally cast concrete pipe, the pipe is formed by rapidly spinning a form containing fluid concrete mix to firmly compact the mix against the wall of the form. In making bell end pipe, it is difiicult to obtain a smooth, dense surface on the inner portion' of the bell because of the tendency of the concrete to move radially outwardly during spinning under the influence of centrifugal force. Consequently, where conditions require a smooth, dense surface within the bell end portion of the pipe, as where the pipe sections are joined by a rubber sealing ring or gasket, it is necessary to finish this portion of the pipe by separate operations after the pipe has been formed centrifugally. One means of doing this is to grind the surface after the pipe has partially cured. This requires considerable time and expense, adding to the cost of the pipe.

An object of my invention is to provide a novel method of casting the pipe centrifugally whereby it is possible to produce a pipe with a bell end having a smooth, dense inner surface within the bell end portion of the pipe without resorting to finishing or grinding operations after the pipe has been spun.

A particular object of my invention is to provide a novel end ring construction for use as a part of the pipe form during the spinning operation which enables the troweling of the interior surface of the bell as a final step in the spinning of the pipe.

Specifically it is an object to provide a novel end ring which includes an inner section and an outer section which are mounted to permit of relative rotation together i with disengageable means for holding the inner section against rotation as the outer section and the pipe form as a whole are rotated.

These and other objects will be apparent from the drawing and the following description.

Referring to the drawing:

Fig. l is an elevational view of a pipe form mounted on rollers for the centrifugal casting of pipe;

Fig. 2 is an end view of the apparatus of Fig. 1;

Fig. 3 is a fragmentary enlarged elevational view, partly in section, of the end portion of a pipe form embodying my invention;

Fig. 4 is a fragmentary plan view in the plane of line 4--4 of Fig. 3; and

Fig. 5 is an enlarged fragmentary sectional view of a portion of the end ring construction taken in the same plane as the sectional portion shown in Fig. 3.

More particularly describing the invention, I show a concrete pipe form 11 consisting of a cylindrical portion 12 mounted on suitable supporting rollers 13, one or more of which may be driven in a conventional manner to impart rotation to the pipe. The cylindrical member 12 of the form is ordinarily split longitudinally so that the pipe formed therein can be readily removed, however, since this forms no part of my invention, it has not been illustrated. At one end of the form I provide a novel bell end ring means generally indicated by numeral 15. This comprises a main end ring member 16 which is detachably secured to the cylindrical member 12, as by bolts 17 spaced circumferentially about the members and passing through a flange 12 on member 12. The main end ring 16 includes an offset peripheral ring portion 18 through which the aforementioned bolts pass and, inwardly of this, a main body 19 which fits within the cylindrical member 12. The body 19 is annular in form and is mounted in a plane normal to the axis of the member 12. At its inner end, the main end ring has a cylindrical inner section 21 which extends axially of the form as a whole.

The main end ring 16 carries a slip ring 23 which at its outer end abuts the body 19 and which has a cylindrical inner face 24 surrounding the section 21 and rotatable with respect thereto. The face 24 terminates at its inner end in a shoulder 25 and beyond this is a second inner cylindrical surface 26 which terminates at a shoulder 27 formed by an inwardly projecting portion 29 on the slip ring. 7 The outer surface 30 of the slip ring is formed to the contour desired in the bell end of the pipe to be formed and, in this connection, concrete 31 has been shown in the form.

The slip ring 23 is provided with a circumferential groove 32 in the surface 24 which accommodates a key member 33 comprising a plate-like main body 34 secured to the section 21 of the main end ring by a screw 36 and having an elongated projection 38 which is relatively loosely received in the groove 32 passing through a suitable aperture 39 provided in the section 21.

The slip ring is also provided with a lug 41 for the purpose to be described. A grease fitting 42 and passage 43 are provided for lubrication of the parts.

In the use of the end ring construction described, the pipe is spun in the ordinary manner with the end ring means 15 attached to the end of the cylindrical form member 12. After the concrete 31 has been sufficiently compacted within the form, the rotation of the form is stopped and means are provided for preventing further rotation of the slip ring. This may be accomplished by providing a stationary supporting structure 44 which carries a pivotally mounted finger 45 movable to the position in which it is shown in Fig. 3 so that the inner end thereof lies in the path of the lug 41 on the slip ring. The form is again rotated and, due to the presence of the finger 45 which lug 41 abuts, the slip ring is prevented from rotating, with the result that the surface of the concrete adjacent the surface 30 of the slip ring is troweled smooth as the concrete is rotated as a body around the slip ring, all parts rotating with the exception of the slip ring.

While I have shown and described a preferred form of my invention, I contemplate that various changes and modifications can be made without departing from the invention, the scope of which is indicated by the claims. For example, it may be desirable to smooth other portions of an article being cast as well as or in lieu of the interior surface of the bell end of a pipe. Thus I may provide a pipe form having a slip ring lo cated at some region other than the location of the one shown.

I claim:

1. In a pipe form for casting concrete pipe or the like by the centrifugal method, a pipe form member defining a tubular space for receiving concrete mix, a slip ring carried by said member having a mold and troweling face defining a part of the surface of the pipe to be cast, said slip ring and said member being relatively rotatable whereby to enable said slip ring to be held stationary by external means while the said member is rotated thereby Patented Mar. 26, 1957- to trowel the concrete adjacent said face of said slip ring.

2. In a pipe form for casting concrete pipe or the like by the centrifugal method, a pipe form member defining a tubular space for receiving concrete mix, a slip ring carried by said member having a mold and trowelirig face defining a part of the surface of the pipe to be cast, said slip ring and said member being relatively rotatable, means for supporting and rotating said pipe form member, and stationary means carried by said last-mentioned means engageable with said slip ring to prevent rotation thereof.

3. In a pipe form for casting concrete pipe by the centrifugal method, a cylindrical pipe form member, an end ring means mounted at one end of said member for defining an end of the pipe, said end ring means including an end ring section attached to said member, and a slip ring mounted on said end ring section for rotation relative thereto, said slip ring having a mold and troweling face disposed to engage the concrete and define a portion of the surface of the pipe.

4. In a pipe form for casting concrete pipe by the centrifugal method having a cylindrical pipe form member, end ring means at the end of said member for forming a bell end on a pipe, comprising a main end ring mounted on said member and projecting radially inward and terminating in an axially inwardly extending portion, a slip ring carried on and surrounding said last-mentioned A. portion of said main end ring, said slip ring and said main end ring being relatively rotatable, and interengaging means on said main end ring and said slip ring retaining said slip ring against axial displacement.

5. Pipe form means as set forth in claim 4 in which said interengaging means on said main end ring and said slip ring comprises a circumferential groove in said slip ring and a key on said main end ring projecting into said groove.

6. In apparatus for casting concrete articles by the centrifugal process, a mold member adapted to hold and shape the concrete, means for rotating said mold member, a slip ring mounted on the mold member, said slip ring and said mold member being relatively rotatable, said slip ring having a mold and troweling face against which the concrete lies in molding said article, and a stationary means mounted independently of said mold member and said slip ring for detachable engagement with said slip ring to prevent rotation thereof with said mold.

References Cited in the file of this patent UNITED STATES PATENTS 1,839,708 Sleight Jan. 5, 1932 2,189,071 Kopp Feb. 6, 1940 2,625,728 Eschenbrenner Jan. 20, 1953 

